Sound reproducer



July 23, 1929. E. H. SMYTHE SOUND REPRODUGER Filed Aug. 17, 1926Patented July 23, 1929.

UNITED STATES. PATENT OFFICE.

EDWIN H. SMYTHE, EVANSTON, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC OOH--PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SOUND BEPBODUCEB.

Application filed August 17, 1926. Serial No. 129,783.

This invention relates to sound reproducers employing direct-actingdiaphragms. The principal object of the inventon is to increase theenergy imparted to the air from a sound radiating surface.

Another object of the invention is to increase the relative movementbetween stationary-and movable walls of a direct-acting soundreproducer.

The invention provides a sound reproducer comprising a movable wall anda stationary supporting wall which are so related that the entiresurface of the movable wall is free to vibrate in response to soundvariations. According to a feature of the invention, sub

stantially all the flexibility necessary to per mit the movable wall tovibrate as a whole for low frequencies is concentrated near theperiphery of the structure and external to the movable 'wall.

In aspecific embodiment of the invention a conical diaphragm, which isdriven at the apex, and a frusto-conical supporting member are connectedbase to base by means of an annular ring of extremely light flexiblematerial, such as 'duralumin, having one or more peripheralcorrugations. The'connecting ring, is rigid in the direction of theplane of the base of the diaphragm, but

is flexible in a direction perpendicular to the plane of the base of thediaphragm, and hence permits the diaphragm to move toward and away fromthe support in responseto sound vibrations, but prevents the diaphragmfrom moving laterally .with respect thereto, and also prevents the.radial relief of air pressures from the space enclosed be tween therelatively movingmember and the relatively stationary member.

ti0n,the bases of the conical diaphragm and frusto-conical supportingmember are cemented directly together, and the required flexibility isobtained by cutting a series of slots close to the extreme outer edge ofthe supporting member.

The inventi Y will be described in connection with the accompanyingdrawing, in which similar reference'characters designate so similarparts in the different views, and in which: i

Fi 1 is aside view, partly in section, of a sound reproducer having aunilaterally flexible peripheral connection between the dia- 58phragmand supporting member;

According to a modification of the inven-,

Fig. 2 is a fragmentary sectional view showmg a modified form ofperipheral connections;

Fig. 3 is a perspective view showing a sound reproducer in whichflexibility is obtained by cutting a series of slots adjacent theperiphery of the supporting member; and

Fig. 4 is a fragmentary view showing a modified method of slotting thesupporting member.

.The sound reproducer shown in Fig. 1 comprises a conical diaphragm 5and a frusto-' V conical supporting member 6 which may be made of lightstifi' material, such as blotting paper. The truncated end of thesupporting member .6 is fastened securely to a suitable standard 7. Themember 8 is provided for connecting a driving member to the apex of theconical diaphragm.

The connection between the diaphragm 5 and the supporting member 6 isprovided by means of an annular ring 9 of extremely light flexiblematerial, such as very light gauge duralumin, having a single deepperipheral corrugation 10. The connecting ring 9 is slightly larger indiameter than the diaphragm and supporting member and is joined onopposite sides-of the corrugation to the outer edges of the diaphragmand supporting member by means of cement 11. If desired, the connectingmember 9 may be provided with a plurality of peripheral corrugations 12as illustrated in Fig. 2.

.The connecting ring 9 may be formed in any suitable manner, such as bypassing aflat strip of very light gauge duraluinin between properlyshaped rollers adapted to form a channel of deeply corrugatedcross-section and circular in form. This construction provides a pleatedconnecting ring which is inherently flexible across the plane of thecorrugation, but is inherently rigid in the direction of the plane ofthe corrugation so that it will readily move in and out but will notbuckle as the entire surface of the diaphragm 100 vibrates. i

In the modification of the invention illustrated in Fig. 3, thediaphragm and supporting member are cemented together base to base. Theflexibility necessary to permit the 5 entire surface of the diaphragm tovibrate is provided by cutting a series of slots 13 disposed as closelyas possible to the extreme outer edge of the frusto-conical supportingmember, and preferably cut obliquely to 1m A I closure,

5 but further reducethe resistance offered by the connecting fingers ofmaterial to axial movement of the diaphragm. A strip of light flexiblecloth 14 is pasted over the slots 13, in order to avoid any substantialair leakage through the slots. The'flexible cloth strip 14 may be pastedonly along its inner and outer edges so that it will not increasethetransverse rigidity of the supporting membar in the zone that it covers.The shape and disposition of the slots adjacent the peripheral margin ofthe supporting member may be varied as desired to reduce the constraintof the supporting member upon the diaphragm for example, .being madetriangular as illustrated in Fig. 4. 7,

Sound vibrations imparted to the apex of the conical diaphragm will tendto cause the entire surface of the diaphragm to vibrate as a unit andproduce a greater relative movement between the surfaces of thediaphragm and supporting members' This produces a greater velocity ofair movement into and out of the space between the diaphragm andsupporting member and improves the respouse in the lower part of themusical scale.

The invention is also capable of other modifications and adaptationswithout departing from the scope and spirit of the invention as definedin the appended claims.

What is claimed is:

1. A sound reproducer comprising a directacting diaphragm and asupporting member forming a partial enclosure, and a unilateral- 11yflexible folded member connecting said iaphragm and said supportingmember.

2. A sound reproducer comprising a directacting conical diaphragm and asupporting member forming a partial enclosure, and means including aV-shaped hinge joining the outer edges of said diaphragm and saidsupporting member to form a closure therebetween.

3. A sound reproducer comprising a conical diaphragm driven at the apex,a supporting member therefor forming a partial? en and a pleated membersecuredfto said diaphragm and said of'th flexible in a directionperpendicular to the plane of the base of'said diaphragm.

4:. A sound reproducer comprisingxa conical diaphragm driven at theapex,l.afrustoconical support for the. base offsaid diaphragm, and meansincluding an annular pleated member of slightly, different outerdiameter than the bases of the diaphragm and the support for connectingsaid support and sad diaphragm together.

ppert ng m era pleated member being rigid in'the direction e plane ofthe base-ofs'aid diaphragm @fa -c ndiment means for rigidly's'upportinggsaidiap means providing a flexible connection. be-

tween said diaphragm and said support, saidmeans being positioned withinthe confines of the outer ed es of said diaphragm and said support andeing rigid in the direction parallel to the base of the diaphragm.

6. A sound reproducer comprising a conical diaphragm driven at the apex,a frustoconical support for the base of said diaphragm, the bases ofsaid diaphragm and said support being substantially equal and spacedapart laterally and means for connecting the basesof said diaphragm andsupport comprising a member which is rigid in the direc tion of theplane of the base of said diaphragm and is flexible in a directionperpendicular to the plane of said base.

7. A sound reproducer comprising a conical diaphragm driven at the apex,a frustoconical support, the bases of said diaphra m and said supportbeing spaced apart an a ring of extremely light resilient materialconnecting the outer edges of said diaphragm and support,

8. A sound reproducer comprising a conical diaphragm driven at the apex,a frustoconical support, and an annular ring of extremely light springmetal having a deep peripheral corrugation connecting the base of saiddiaphragm to the base of said support.

9. In a sound reproducing device, the combination of two dished membersof equal base diameters, one of said members having an aperture therein,a link connecting the bases of said members together, said link beingflexible in the direction of the axes of said members and rigid inthe-direction perpendicular to the axes of said members, means forrigidly supporting one of said dished members at its aperture, and meansconnected to a point on the surfacefof th other of a dm rs. f m

thereto.

forte T noi i lar i mam bet, meansconnected to. spam for impartingvibrational forces thereto.

err-tad .f tits ape are, and 3.1115?- "the other of'said col odal-shaped ineinbers In witness whereof,"I hereunto subscribe my namethis 12 day of August A. D., 1926.

. EDWIN H.

